Photographic film



A. F. SULZER.

PHOTGGRAPHIC FILM.

APPLICATION FILED FEB. 21 I92I. l 3&368, Patented (Ict. I7, T922,

INVENTOR ATTORNEY Patented @et il?, T922.,

NETE@ STATES PATENT @EETCEO ALBERT F. SULZER, OF ROCHESTER, NEW YORK, ASSIGNOR. TO EASTMAN KODAK COMPANY, OF ROCHESTER, NEW YORK, A CORPORATION OF NEW YORK.

PHOTOGRAPHIC FILM.

Application led February 21, 1921.

To all whom it may concern Be it known that I, ALBERT F. SULZER, a citizen of the United States of America, residing at Rochester, in the county of Monroe and State of New York, have invented certain new and useful Improvements in Photographic Films, of which the following is a full, clear, and exact specification.

This invention relates to photographic film and to the base or support for such film. The principal object of this invention is to provide a film having the qualities desirable in commercial practice, which will likewise be so made that markings due to electrical discharges are prevented or very greatly minimized. Other objects` will hereinafter appear.

In the handling of sensitive photographic lm, particularly that of the usual kind which includes a nitrocellulose support or base, characteristic lines or patches some times appear on development, due to electrical discharges, which occur when the film is manipulated. lVhile the defect may crop out during manufacture, it is particularly troublesome in the motion picture field, especially when making negative film strips. Tt is customarily referred to as static and will be so designated hereinafter.

While several changes in motion picture cameras have been suggested for preventing static, it is highly desirable to preventthe trouble by a proper constitution of the film, so that the latter may be employed in any commercial apparatus without the necessity of special precautions.

I have discovered that film having strong anti-static properties may be prepared by adding certain substances to the nitrocellulose film base or support, and then coating the rear face of it with a suitable antistatic layer. Thus I may coat film of the kind indicated in the co-pending applications of Paul C. Seel, Serial Nos. 434,353 and 434,354, both filed Dec. 31, 1920, on the rear face or surface opposite the sensitive photographic coating with an anti-static insoluble backing. This backing may, for example, be of cellulose acetate, or cellulose ether, or various mixtures of these substances with each other or with cellulose nitrate, as indicated in U. S. Patent No. 1,232,702, Lovejoy, July 10, 1917, and the applications of Albert F. Sulzer, Serial Serial N0. 446.784.

Nos. 446,782 and 446,783 both filed Feb. 21, 1921.

. In the 'accompanying drawing the figure 1s a sectional view on an exaggerated scale of a film embodyingmy invention.

The support 1 carries the sensitive layer 2 on one face and the insoluble anti-static backing 3 on the other.

A photographie film comprising a photographically sensitive layer and a nitrocellulose support containing hygroscopic metallic salts, together with water and certain co-operating agents is a very useful product, and static is prevented with great effectiveness. But when the hygroscopic substances and the water are present in the higher amounts in their range of proportions, there may be a tendency in certain warm and damp climates for the water to appear on the rear face of the film and affect the sensitive emulsion with which it contacts when the film is coiled up. By coating the rear face of the film with an antistatic insoluble backing, I not only provide the film with a double insurance against static, but at the same time remove any risk of this injurious sweating. There isv also a stronger tendency for the water to remain sealed in the film base in dry climates.

By way of illustration, the nitrocellulose base may be manufactured from a dope comprising 100 parts of nitrocellolose, 250 parts of acetone, 250 parts of methyl alcohol, 40 parts of fusel oil, l0 parts of caniphor, 1 part of sodium hypophosphite, 5 parts of glycerin and 5 parts of water.

Equivalents may be substituted and the proeportions widely varied, as indicated in the applications of Paul C. Seel hereinabove referred to.

Upon this hygroscopic anti-static film base there is coated the usual gelatino-silver haloid sensitive emulsion. On the face opposite the emulsion there is deposited a cellulosic anti-static layer or coating which may, for instance, be cellulose acetate of the kind which is soluble in acetone. It is very thin. The coating maybe made from a weak solution of the acetate in a mixture of acetone and ethyl alcohol, the latter being sufficient-ly diluted, so that the composition is clear and the cellulose acetate not precipitated.

The coating may likewise be of cellulose ether, in which ease l prefer a dilute composition or the type indicated in the Sulzer applications hereinabove mentioned. For instance, may use a Composition eomprising 90 parts of ethyl cellulose, (300 parts ot' ethyl alcohol. 900 parts of chloroform and 300() parts ot' acetone. Uf course, equivalent coatings disclosed in the Lovejoy patent and in the Sulzer applications may be substituted. All such coatings are substantially 11on-s\veating,-that is, their outer surfaces remain satisfactorily 'free from moisture even in a hot and humid atmosphere.

Having thus described my invention, what' l elaini as neiv 'and desire 'to secure by ,Letters Patent is:

l. photographie lilin comprising a sensitive coating and an anti-statichygroseopie nitrocellulose supportI therefor, the face ot' said support opposite said sensitive coating being provided with a non-sweating insolun ble anti-statie coating.

2. A photographic film comprising a sensitive coating and an anti-static. nitrocellulose support therefor, which Contains a hygroseopie substance and Water, the base ot' said support opposite said sensitive coating being provided with a non-sweating anti-static coating.

3. A photographic film comprising a sensitive coating and an anti-statichygroseopio nitrocellulose support therefor, the face of said support opposite said sensitive coating being provided with a cellulosic` anti-static non-sweating Coating. A

4. A. photographie film comprising a sensitive coating and an anti-static nitrocellulose support therefor, which contains an inert h vgrosropic metallic salt, glycerin and water, the face opposite said sensitive coating being provided with a coating of oellulose acetate.

Signed at Rochester, New York, this 15th day of February, 1921.

ALBERT l?. SULZER. 

